Erscheinungsjahr 2020

Anzahl der Treffer: 69
Erstellt: Thu, 28 Mar 2024 23:15:20 +0100 in 0.0798 sec


Söllner, Fritz;
[Rezension von: Rindermann, Heiner, 1966-, Cognitive capitalism]. - In: Public choice. - New York, NY : Springer Science+Business Media LLC, [1968]- , ISSN: 1573-7101 , ZDB-ID: 1475723-0, ISSN 1573-7101, Bd. 187 (2021), 3/4, S. 527-531

https://doi.org/10.1007/s11127-020-00802-9
Xu, Rui; Du, Lei; Adekoya, David; Zhang, Gaixia; Zhang, Shanqing; Sun, Shuhui; Lei, Yong
Well-defined nanostructures for electrochemical energy conversion and storage. - In: Advanced energy materials, ISSN 1614-6840, Bd. 11 (2021), 15, 2001537, insges. 53 S.

Electrochemical energy conversion and storage play crucial roles in meeting the increasing demand for renewable, portable, and affordable power supplies for society. The rapid development of nanostructured materials provides an alternative route by virtue of their unique and promising effects emerging at nanoscale. In addition to finding advanced materials, structure design and engineering of electrodes improves the electrochemical performance and the resultant commercial competitivity. Regarding the structural engineering, controlling the geometrical parameters (i.e., size, shape, hetero-architecture, and spatial arrangement) of nanostructures and thus forming well-defined nanostructure (WDN) electrodes have been the central aspects of investigations and practical applications. This review discusses the fundamental aspects and concept of WDNs for energy conversion and storage, with a strong emphasis on illuminating the relationship between the structural characteristics and the resultant electrochemical superiorities. Key strategies for actualizing well-defined features in nanostructures are summarized. Electrocatalysis and photoelectrocatalysis (for energy conversion) as well as metal-ion batteries and supercapacitors (for energy storage) are selected to illustrate the superiorities of WDNs in electrochemical reactions and charge carrier transportation. Finally, conclusions and perspectives regarding future research, development, and applications of WDNs are discussed.



https://doi.org/10.1002/aenm.202001537
Schweser, Thomas; Stiebitz, Michael
Partitions of hypergraphs under variable degeneracy constraints. - In: Journal of graph theory, ISSN 1097-0118, Bd. 96 (2021), 1, S. 7-33

https://doi.org/10.1002/jgt.22575
Song, Xinya; Cai, Hui; Jiang, Teng; Sennewald, Tom; Kircheis, Jan; Schlegel, Steffen; Noris Martinez, Leonel; Benzetta, Youcef; Westermann, Dirk
Research on performance of real-time simulation based on inverter-dominated power grid. - In: IEEE access, ISSN 2169-3536, Bd. 9 (2021), S. 1137-1153

https://doi.org/10.1109/ACCESS.2020.3016177
Hunold, Alexander; Machts, René; Haueisen, Jens
Head phantoms for bioelectromagnetic applications: a material study. - In: Biomedical engineering online, ISSN 1475-925X, Bd. 19 (2020), 87, S. 1-14

Assessments of source reconstruction procedures in electroencephalography and computations of transcranial electrical stimulation profiles require verification and validation with the help of ground truth configurations as implemented by physical head phantoms. For these phantoms, synthetic materials are needed, which are mechanically and electrochemically stable and possess conductivity values similar to the modeled human head tissues. Three-compartment head models comprise a scalp layer with a conductivity range of 0.137 S/m to 2.1 S/m, a skull layer with conductivity values between 0.066 S/m and 0.00275 S/m, and an intracranial volume with an often-used average conductivity value of 0.33 S/m. To establish a realistically shaped physical head phantom with a well-defined volume conduction configuration, we here characterize the electrical conductivity of synthetic materials for modeling head compartments. We analyzed agarose hydrogel, gypsum, and sodium chloride (NaCl) solution as surrogate materials for scalp, skull, and intracranial volume. We measured the impedance of all materials when immersed in NaCl solution using a four-electrode setup. The measured impedance values were used to calculate the electrical conductivity values of each material. Further, the conductivities in the longitudinal and transverse directions of reed sticks immersed in NaCl solution were measured to test their suitability for mimicking the anisotropic conductivity of white matter tracts.



https://doi.org/10.1186/s12938-020-00830-y
Budzinski, Oliver; Gänßle, Sophia; Stöhr, Annika
The proposal of a 10th amendment of German competition law: interventionism or laissez-faire? :
Der Entwurf zur 10. GWB Novelle: Interventionismus oder Laissez-faire?. - In: List Forum für Wirtschafts- und Finanzpolitik, ISSN 2364-3943, Bd. 46 (2020), 2, S. 157-184

https://doi.org/10.1007/s41025-020-00204-1
Rochyadi-Reetz, Mira; Budiono, Olivia Deskarina; Wolling, Jens
Regularity of a crisis: media framing of the 2015 transboundary haze issue in Indonesia, Singapore, and Malaysia. - In: Jurnal Komunikasi, ISSN 0128-1496, Bd. 36 (2020), 2, S. 415-433
Richtiger Name der Verfasserin: Olivia Deskarina Budiono

The problem of the haze caused by huge forest fires persists as an annual transboundary problem for Indonesia and the rest of Southeast Asia. In 2015, the problem was worse than ever before, affecting many countries in the Association of Southeast Asian Nations (ASEAN) and causing respiratory ailments for more than half a million Indonesians. This study explores the media framing of the haze problem in Indonesia from June to December 2015. Using Entman’s framing approach, it investigates how media outlets from Indonesia, Malaysia, and Singapore covered the crisis. Articles from six online media outlets published in these three countries were analysed. Using cluster analysis, this research identified three frames as follows: (1) crisis frame, (2) immediate action frame, and (3) regular problem frame. The first cluster/frame consists of articles giving high salience to all problems and causes of the forest fires provoking the haze. In contrast, the second frame mostly ignores causes and problems and focuses almost exclusively on the need for immediate action. The third frame, which represents more than 60% of the articles, covers the haze problem as a regular issue without emphasizing prominently either the different aspects of the problem itself or its causes and solutions. Further results show that the media in Singapore and Malaysia used the crisis frame more often than the media in Indonesia.



https://doi.org/10.17576/JKMJC-2020-3602-25
Boeck, Thomas; Sanjari, Seyed Loghman; Becker, Tatiana
Parametric instability of a magnetic pendulum in the presence of a vibrating conducting plate. - In: Nonlinear dynamics, ISSN 1573-269X, Bd. 102 (2020), 4, S. 2039-2056

A pendulum with an attached permanent magnet swinging in the vicinity of a conductor is a typical experiment for the demonstration of electromagnetic braking and Lenz law of induction. When the conductor itself moves, it can transfer energy to the pendulum. An exact analytical model of such an electromagnetic interaction is possible for a flat conducting plate. The eddy currents induced in the plate by a moving magnetic dipole and the resulting force and torque are known analytically in the quasistatic limit, i.e., when the magnetic diffusivity is sufficiently high to ensure an equilibrium of magnetic field advection and diffusion. This allows us to study a simple pendulum with a magnetic dipole moment in the presence of a horizontal plate oscillating in vertical direction. Equilibrium of the pendulum in the vertical position can be realized in three cases considered, i.e., when the magnetic moment is parallel to the rotation axis, or otherwise, its projection onto the plane of motion is either horizontal or vertical. The stability problem is described by a differential equation of Mathieu type with a damping term. Instability is only possible when the vibration amplitude and the distance between plate and magnet satisfy certain constraints related to the simultaneous excitation and damping effects of the plate. The nonlinear motion is studied numerically for the case when the magnetic moment and rotation axis are parallel. Chaotic behavior is found when the eigenfrequency is sufficiently small compared to the excitation frequency. The plate oscillation typically has a stabilizing effect on the inverted pendulum.



https://doi.org/10.1007/s11071-020-06054-y
Angermeier, Sebastian; Karcher, Christian
Model-based condenser fan speed optimization of vapor compression systems. - In: Energies, ISSN 1996-1073, Bd. 13 (2020), 22, 6012, S. 1-26

Vapor compression systems (VCS) cover a wide range of applications and consume large amounts of energy. In this context, previous research identified the optimization of the condenser fans speed as a promising measure to improve the energy efficiency of VCS. The present paper introduces a steady-state modeling approach of an air-cooled VCS to predict the ideal condenser fan speed. The model consists of a hybrid characterization of the main components of a VCS and the optimization problem is formulated as minimizing the total energy consumption by respectively adjusting the condenser fan and compressor speed. In contrast to optimization strategies found in the literature, the proposed model does not relay on algorithms, but provides a single optimization term to predict the ideal fan speed. A detailed experimental validation demonstrates the feasibility of the model approach and further suggests that the ideal condenser fan speed can be calculated with sufficient precision, assuming constant evaporating pressure, compressor efficiency, subcooling, and superheating, respectively. In addition, a control strategy based on the developed model is presented, which is able to drive the VCS to its optimal operation. Therefore, the study provides a crucial input for set-point optimization and steady-state modeling of air-cooled vapor compression systems.



https://doi.org/10.3390/en13226012
Chehreh, Abootorab; Grätzel, Michael; Bergmann, Jean Pierre; Walther, Frank
Fatigue behavior of conventional and stationary shoulder friction stir welded EN AW-5754 aluminum alloy using load increase method. - In: Metals, ISSN 2075-4701, Bd. 10 (2020), 11, 1510, insges. 11 S.

https://doi.org/10.3390/met10111510